1. Field of the Invention
The invention relates to wear resistant lubricants using a premium synthetic base stock derived from waxy Fischer-Tropsch hydrocarbons, their preparation and use. More particularly the invention relates to a wear resistant lubricant, such as a lubricating oil, comprising an admixture of an effective amount of an antiwear additive and a synthetic base stock, wherein the base stock is prepared by hydroisomerizing waxy, Fischer-Tropsch synthesized hydrocarbons and, in the case of a wear resistant lubricating oil, dewaxing the hydroisomerate to reduce the pour point.
2. Background of the Invention
Internal combustion engine lubricating oils require the presence of antiwear additives in order to provide adequate antiwear protection for the engine. Increasing specifications for engine oil performance have exhibited a trend for increasing antiwear properties of the oil. While there are many different types of antiwear additives, for several decades the principal antiwear additive for internal combustion engine crankcase oils has been a metal alkylthiophosphate and more particularly a metal dialkyldithiophosphate in which the primary metal constituent is zinc, or zinc dialkyldithiophosphate (ZDDP). The ZDDP is typically used in amounts of from about 0.7 to 1.4 wt. % of the total lube oil composition. However, it has been found that the phosphorus from these additives has a deleterious effect on the catalyst in catalytic converters and also on oxygen sensors in automobiles. Furthermore, besides being expensive, some antiwear additives add to engine deposits, which causes increased oil consumption and an increase in particulate and regulated gaseous emissions. Therefore, reducing the amount of metal dialkyldithiophosphate such as ZDDP in the oil without compromising its wear performance would be desirable. One solution to this problem is to use expensive supplementary, phosphorus-free antiwear additives as set forth, for example, in U.S. Pat. No. 4,764,294. It would be an improvement to the art if the amount of antiwear additive, such as metal dialkyldithiophosphates or other expensive additives could be reduced without having to resort to the use of the supplementary additives, or if the amount of supplemental additives could be reduced without compromising engine protection. It would also be an improvement to the art if increased wear resistance could be achieved without having to substantially increase the amount of antiwear additives in the oil.